122-3401 100-3259 CAT Hydraulic Piston Pump for 446 446B

Product Overview

Technical Specifications

• Cross-Reference Part Numbers: 100-3259, 259-0815, 122-3401, 220-5623, 6E-5072 (Caterpillar OEM replacement)
• Pump Type: Variable Displacement Axial Piston Pump
• Rated Working Pressure: 35 MPa (350 bar)
• Peak Pressure: 40 MPa (400 bar)
• System Matching Pressure: 228 bar (aligned with OEM 446/446B hydraulic relief setting)
• Maximum Operating Speed: 2200 rpm (matched to engine rated output speed)
• Control Mode: Load Sensing + Pressure Compensation, Closed Center Hydraulic System
• Mounting Interface: OEM standard flange and port dimensions for full direct interchangeability
• Compatible Machines: Caterpillar 446, 446B Backhoe Loaders; compatible with 416B/428B/438B, 420D/430D series backhoe loaders and selected motor graders & excavators (subject to specific part number)

Key Technical Advantages

1. Micron-level Precision Machining & 100% Direct Interchangeability

   Core friction pairs including cylinder block, valve plate and piston slipper are processed with high-precision CNC honing and super-finish grinding, with dimensional tolerance controlled at micron level. The mounting flange, shaft extension and port positions fully replicate original drawings, enabling damage-free installation and significantly reducing equipment downtime and retrofitting cost.

2. High Volumetric Efficiency & Load Sensing Energy Saving

   Optimized kidney-shaped valve port structure and slipper hydrostatic support design minimize internal leakage, achieving volumetric efficiency above 94% under rated working conditions. The load sensing control mechanism adjusts displacement in real time according to flow demand of actuators, eliminating unnecessary overflow loss and effectively reducing equipment fuel consumption.

3. Heavy-Duty Material Configuration for Extended Service Life

   The drive shaft is made of high-strength alloy structural steel with carburizing and quenching treatment, reaching surface hardness of HRC58-62. It is paired with heavy-duty tapered roller bearings for excellent radial impact resistance. The cylinder valve pair adopts high-strength cast iron and copper alloy matching scheme with outstanding wear resistance, effectively prolonging the overall service life of the pump under continuous high-pressure operation.

4. Full Working Condition Factory Testing for Stable Reliability

   Each pump passes 100% simulated working condition bench test before delivery, including multiple inspections such as rated pressure holding, peak pressure shock, high and low speed cycle, and oil temperature rise verification. It operates stably within ambient temperature range of -20℃ to 100℃, adapts to complex field working environments and reduces on-site failure risk.

5. Low Noise & Vibration Damping Design

   The internal flow channel is optimized by fluid dynamics design to reduce hydraulic shock and cavitation noise. The pump housing is equipped with vibration damping structure, controlling operating noise below 82dB. It also has built-in pressure overload buffer mechanism to absorb instantaneous system pressure shock and protect the pump and downstream hydraulic components.

Application Areas

• Municipal engineering: Backhoe loader hydraulic systems for road construction, pipeline excavation, site grading and other operations
• Mining operations: Material handling, slope trimming and site cleaning equipment in open-pit mines
• Agricultural infrastructure: Small construction equipment for farmland water conservancy, land consolidation and rural construction
• Ports and yards: Engineering vehicles for cargo handling, equipment maintenance and bulk cargo loading
• Other scenarios: Corresponding part numbers fit Caterpillar motor graders, small and medium excavators and other hydraulic systems

Expert Maintenance Tips

1. Installation Calibration Requirements

   Ensure the coaxiality error between the pump shaft and engine power output shaft is ≤0.1mm during installation, to avoid premature wear of shaft seal and bearing caused by excessive radial force. Thoroughly clean the ports and connecting flange surface before installation, and prevent impurities such as iron filings and dust from entering the pump body. Fill the pump housing with clean hydraulic oil before first startup to avoid dry friction damage to the valve pair.

2. Hydraulic Oil Specifications

   Use high-quality anti-wear hydraulic oil compliant with ISO VG46 standard, with oil cleanliness reaching NAS grade 8 or above. Ensure the suction pipeline is well sealed to avoid air intake and cavitation. The normal operating temperature range of hydraulic oil is 30℃ to 80℃; long-term operation above 90℃ will accelerate oil deterioration and seal aging.

3. Regular Maintenance Interval

   Check oil cleanliness and oil level every 500 working hours, and inspect pipeline for leakage. Replace hydraulic oil and return filter every 2000 working hours, and clean the suction filter at the same time. It is recommended to disassemble and inspect the wear condition of internal friction pairs every 4000 working hours to predict failure risks in advance.

4. Common Troubleshooting

   If output pressure is insufficient, first check whether the suction filter is clogged or the relief valve is stuck. If abnormal noise occurs, focus on checking whether oil is aerated or bearing is worn. Do not operate the pump with faults for a long time without troubleshooting, to avoid irreversible damage to the pump body.